Search results for "CHS"
showing 10 items of 313 documents
Mismatch brain response to speech sound changes in rats
2011
Understanding speech is based on neural representations of individual speech sounds. In humans, such representations are capable of supporting an automatic and memory-based mechanism for auditory change detection, as reflected by the mismatch negativity of event-related potentials. There are also findings of neural representations of speech sounds in animals, but it is not known whether these representations can support the change detection mechanism analogous to that underlying the mismatch negativity in humans. To this end, we presented synthesized spoken syllables to urethane-anesthetized rats while local field potentials were epidurally recorded above their primary auditory cortex. In a…
Unusual resistive states of multiband superconductors in the effective field theory approach
2020
Starting from the microscopic approach based on multiband Keldysh-Usadel kinetic theory we derive the minimal field-theoretical model equivalent to the time-dependent Ginzburg-Landau theory. We discuss the properties of resistive states determined by the ratio of electric field relaxation length to the superconducting coherence length. In contrast to the well-studied single-band systems we find that this ratio can vary in wide limits in multiband superconductors. As a result, the properties of resistive states in multiband superconductors can be tuned by the microscopic parameters such as the ratio of diffusion coefficients and pairing constants in different bands. As an example we consider…
Resistive state triggered by vortex entry in YBa 2 Cu 3 O 7−δ nanostructures
2014
We have realized YBa2Cu3O7-delta nanowires and nano Superconducting Quantum Interference Devices (nanoSQUID). The measured temperature dependence of the wire resistances below the superconducting transition temperature has been analyzed using a thermally activated vortex entry model valid for wires wider than the superconducting coherence length. The extracted zero temperature values of the London penetration depth, lambda(0) similar or equal to 270 +/- 15 nm, are in good agreement with the value obtained from critical current modulations as a function of an externally applied magnetic field in a nanoSQUID implementing two nanowires.
Phase Slip Phenomena in Ultra-Thin Superconducting Wires
2006
We present results on phase-slip phenomena in a superconducting wire which can be considered as quasi-one dimensional (1D) if its characteristic transverse dimension \( \sqrt \sigma\) (√ being the cross section) is smaller than the coherence length Λ(T). The shape of the bottom part of the resistive transition R(T) of a 1D superconducting strip is described by the model of phase slips activation. If the wire is infinitely long, then there is always a finite probability that a small part of the sample is instantly driven normal.
Resistive State of Superconductor-Ferromagnet-Superconductor Josephson Junctions in the Presence of Moving Domain Walls
2019
We describe resistive states of the system combining two types of orderings---a superconducting and a ferromagnetic one. It is shown that in the presence of magnetization dynamics such systems become inherently dissipative and in principle cannot sustain any amount of the superconducting current because of the voltage generated by the magnetization dynamics. We calculate generic current-voltage characteristics of a superconductor-ferromagnet-superconductor Josephson junction with an unpinned domain wall and find the low-current resistance associated with the domain wall motion. We suggest the finite slope of Shapiro steps as the characteristic feature of the regime with domain wall oscillat…
Experimental Study of the Fluctuation-Governed Resistive State in Quasi-One-Dimensional Superconductors
2011
Physical properties of quasi-one-dimensional superconducting channels (nanowires) can differ significantly from those of bulk superconductors. The reason behind is the impact of thermal and quantum fluctuations. In the particular case of resistive measurements the fluctuations may significantly broaden the superconducting transition R(T). Here we review the activities in the field with main emphasis on experiment, while brief theoretical background is also presented.
Low-Frequency Imaginary Impedance at the Superconducting Transition of 2H - NbSe2
2020
The superconducting transition leads to a sharp resistance drop in a temperature interval that can be a small fraction of the critical temperature ${T}_{c}$. A superconductor exactly at ${T}_{c}$ is thus very sensitive to all kinds of thermal perturbation, including the heat dissipated by the measurement current. We show that the interaction between electrical and thermal currents leads to a sizable imaginary impedance at frequencies of the order of tens of hertz at the resistive transition of single crystals of the layered material $2H$-${\mathrm{Nb}\mathrm{Se}}_{2}$. We explain the result using models developed for transition-edge sensors. By measuring under magnetic fields and at high cu…
Superconductivity in high‐quality (Hg 0.9 Re 0.1 )Ba 2 CaCu 2 O 6+ δ HTSC thin films
2004
High-quality epitaxial (Hg0.9Re0.1)Ba2CaCu2O6+δ (HgRe-1212) HTS thin films were successfully prepared using pulsed laser deposition (PLD) of the Re0.1Ba2CaCu2O6+δ precursor and subsequent Hg vapor annealing. The thin films exhibit a sharp superconducting transition at Tc ≈ 120 K. The resistive transitions have been investigated in magnetic fields up to 6 T parallel and perpendicular to the c-axis. We have determined the activation energy of thermally activated flux-motion for both magnetic field orientations. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Vortex-creep activation energy in YBa2Cu3O7/PrBa2Cu3O7 superlattices
2010
Abstract YBa 2 Cu 3 O 7 /PrBa 2 Cu 3 O 7 (YBCO/PBCO) superlattices with a different ratio of the superconducting and insulating layer thicknesses were prepared by high pressure dc sputtering. The vortex-creep activation energy U 0 was determined by analyzing the in-plane resistive transition of 200 μm wide bridges with the external magnetic field B oriented along the c axis. It was found that U 0 is proportional to the thickness of the YBCO layers, and does only weakly depend on the PBCO layer thickness, when the latter exceeds two unit cells. We observed a change in the variation of U 0 with the current I in the specimen: U 0 exhibits a plateau in the low- I region, then decreases signific…
The Gentle Art of Counselling Monarchs (1560-1655)
2017
This article has no abstract. peerReviewed